Diffusers are a great way to fragrance your home without having to keep an eye on a candle. Reed diffusers provide a constant fragrance without a flame. The fragrance of an essential oil diffuser can be intensified by flipping the reeds. You can flip a few reeds every few days or all the reeds everyday depending on the size of your space and how strong you like your fragrances. The fragrance oil in the diffuser evaporates over time and will last anywhere from 4 to 9 months depending on how many reeds you flip and how often you flip them.